#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <ctype.h>
#include <time.h>
#include <pthread.h>
#include <getopt.h>
#include <libgen.h>
#include <sys/types.h> 
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <poll.h>
#define ARRAY_SIZE(x) (sizeof(x)/sizeof(x[0]))
static inline void print_usage(char *progname);
int socket_server_init(char *listen_ip, int listen_port);
int main(int argc, char **argv)
{
 int listenfd, connfd;
 int serv_port = 0;
 int daemon_run = 0;
 char *progname = NULL;
 int opt;
 int rv;
 int i, j;
 int found;
 int max;
 char buf[1024];
 struct pollfd fds_array[1024];
 struct option long_options[] =
 { 
 {"daemon", no_argument, NULL, 'b'},
 {"port", required_argument, NULL, 'p'},
 {"help", no_argument, NULL, 'h'},
 {NULL, 0, NULL, 0}
 }; 
 progname = basename(argv[0]);
 /* Parser the command line parameters */
 while ((opt = getopt_long(argc, argv, "bp:h", long_options, NULL)) != -1)
 {  switch (opt)
 { 
 case 'b':
 daemon_run=1;
 break;
 case 'p':
 serv_port = atoi(optarg);
 break;
 case 'h': /* Get help information */
 print_usage(progname);
 return EXIT_SUCCESS;
 default:
 break;
 } 
 } 
 if( !serv_port )
 { 
 print_usage(progname);
 return -1;
 }
 if( (listenfd=socket_server_init(NULL, serv_port)) < 0 )
 {
 printf("ERROR: %s server listen on port %d failure\n", argv[0],serv_port);
 return -2;
 }
 printf("%s server start to listen on port %d\n", argv[0],serv_port);
 /* set program running on background */
 if( daemon_run )
 {
 daemon(0, 0);
 }
 for(i=0; i<ARRAY_SIZE(fds_array) ; i++)
 {
 fds_array[i].fd=-1;
 }
 fds_array[0].fd = listenfd;
 fds_array[0].events = POLLIN;
 max = 0;
 for ( ; ; )
 {
 /* program will blocked here */
 rv = poll(fds_array, max+1, -1);
 if(rv < 0)
 {
 printf("select failure: %s\n", strerror(errno));
 break;
 }
 else if(rv == 0)
 {
 printf("select get timeout\n");
 continue;
 }
 /* listen socket get event means new client start connect now */
 if (fds_array[0].revents & POLLIN)
 {
 if( (connfd=accept(listenfd, (struct sockaddr *)NULL, NULL)) < 0)
 {
 printf("accept new client failure: %s\n", strerror(errno));
 continue; }
 found = 0;
 for(i=1; i<ARRAY_SIZE(fds_array) ; i++)
 {
 if( fds_array[i].fd < 0 )
 {
 printf("accept new client[%d] and add it into array\n", connfd );
 fds_array[i].fd = connfd;
 fds_array[i].events = POLLIN;
 found = 1;
 break;
 }
 }
 if( !found )
 {
 printf("accept new client[%d] but full, so refuse it\n", connfd);
 close(connfd);
 continue;
 }
 
 max = i>max ? i : max;
 if (--rv <= 0)
 continue;
 }
 else /* data arrive from already connected client */
 {
 for(i=1; i<ARRAY_SIZE(fds_array); i++)
 {
 if( fds_array[i].fd < 0 )
 continue;
 if( (rv=read(fds_array[i].fd, buf, sizeof(buf))) <= 0)
 {
 printf("socket[%d] read failure or get disconncet.\n", fds_array[i].fd);
 close(fds_array[i].fd);
 fds_array[i].fd = -1;
 }
 else
 {
 printf("socket[%d] read get %d bytes data\n", fds_array[i].fd, rv);
 /* convert letter from lowercase to uppercase */
 for(j=0; j<rv; j++)
 buf[j]=toupper(buf[j]);
 if( write(fds_array[i].fd, buf, rv) < 0 )
 {
 printf("socket[%d] write failure: %s\n", fds_array[i].fd, strerror(errno));
 close(fds_array[i].fd);
 fds_array[i].fd = -1;
 }
 }
 }
 }
 }
CleanUp:
 close(listenfd);
 return 0;
}
static inline void print_usage(char *progname)
{
 printf("Usage: %s [OPTION]...\n", progname);
 
 printf(" %s is a socket server program, which used to verify client and echo back string from it\n",
progname); printf("\nMandatory arguments to long options are mandatory for short options too:\n");
 
 printf(" -b[daemon ] set program running on background\n");
 printf(" -p[port ] Socket server port address\n");
 printf(" -h[help ] Display this help information\n");
 
 printf("\nExample: %s -b -p 8900\n", progname);
 return ;
}
int socket_server_init(char *listen_ip, int listen_port)
{
 struct sockaddr_in servaddr;
 int rv = 0;
 int on = 1;
 int listenfd;
 if ( (listenfd = socket(AF_INET, SOCK_STREAM, 0)) < 0)
 {
 printf("Use socket() to create a TCP socket failure: %s\n", strerror(errno));
 return -1;
 }
 /* Set socket port reuseable, fix 'Address already in use' bug when socket server restart */
 setsockopt(listenfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
 memset(&servaddr, 0, sizeof(servaddr));
 servaddr.sin_family = AF_INET; 
 servaddr.sin_port = htons(listen_port);
 if( !listen_ip ) /* Listen all the local IP address */
 {
 servaddr.sin_addr.s_addr = htonl(INADDR_ANY); 
 }
 else /* listen the specified IP address */
 {
 if (inet_pton(AF_INET, listen_ip, &servaddr.sin_addr) <= 0)
 {
 printf("inet_pton() set listen IP address failure.\n");
 rv = -2;
 goto CleanUp;
 }
 }
 if(bind(listenfd, (struct sockaddr *) &servaddr, sizeof(servaddr)) < 0)
 {
 printf("Use bind() to bind the TCP socket failure: %s\n", strerror(errno));
 rv = -3;
 goto CleanUp;
 }
 if(listen(listenfd, 13) < 0)
 {
 printf("Use bind() to bind the TCP socket failure: %s\n", strerror(errno));
 rv = -4;
 goto CleanUp;
 }
CleanUp:
 if(rv<0)
 close(listenfd);
 else
 rv = listenfd;
 return rv;
}
